Detonator tester



Dec. v2, 1947. A. M. BIGGAR DETONATOR TESTER Filed Feb. 23, 1945 Figure 2.

Patented Dec. 2, 1947 UNITED STATE .DE'roNA'ron TESTER Allan M. Biggar, Arlington, Va., assignor to the United States of America, as represented by the Secretary of War Application February 23, 1945, Serial No. 579,482

` 7 claims. (ci. 'za- 167) (Granted under the act of March 3, 1883, as

amended April 30, 1928'; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, Without the payment to me of any royalty thereon.

This -invention relates to the testing of detonators.

A purpose of the invention is to provide a device for testing of detonators.

Another purpose of the invention is to Provide a means of applying a hot flash of iiame to a detonator.

A further purpose of the invention is to provide a support for a detonator while the detonator is being tested.

Another purpose ofthe invention is to provide a source of a hot flash of flame for testing detonators.

Other purposes or' the invention will become apparent from the following description and Figure 2 is a detailed partly sectional elevation oi the detonator support shown in Figure 1.

yFigure 3 is a detailed sectional elevation of the iiash producer shown in Figure 1.

Figure 4 is a longtudinal sectional view of a detonator.

Figure 5 is a view taken along the line 5-5 of Figure 6 is a viewtaken along the line 6-6 of Figure 3.

Figure 7 is a view taken along the line 'l-'l of Figure 3. l

Figure 8 is a perspective detail view of the plastie detonator holder shown in Figures 1 and 2, and

Figure 9 is a perspective detail view of a holding member 94.

In the manufacture of detonators it is necessary to determine their degree of sensitivity to the application of heat. This is of particular necessity when the detonators are of the type intended to be actuated by heat applied from a source external to the detonator. One example of the latter is a detonatorrcontaining lead azide, or lead azide and tetryl, and commonly interposed in an artillery ammunition projectile fuse between the end of the explosive delay train and the booster charge. It is necessary for the deto' i nator to be sensitive enough to be actuatedl by 4 vice by means of which detonators may be subjected to heat for test purposes.

Referringlto the drawingsfthere is a platform or base 2 made of iron or steel, or other suitable material, on the upper surface 4 of top member i 5 of which are located a support 6 for a detonator, and a device 8 for producing and projecting burning gases or flame by means of explosion, the device 8 being designated herein as a flash producer or flame projector. The platform 2 has legs or supports 3.

The vash producer 8 has a vertical cylindrical housing or body i3. The housing I0 has a centra] cylindrical recess I2 havinga lower reduced portion I4 and an upper enlarged portion I. In the enlarged portion IS is placed a rubber washer or gasket I8 having an outside diameter equal to the diameter of the portion I6 and an inside diameter equal to that of the reduced portion I4. Above the washer i8 is placed a nietal disk having a central bore 22 in which is placed a percussion primer 24. The bore 22 has its upper extremity 23 slightly enlarged to receive and support the rim of the primer 24 as shown. Above the disk 20 ls placed a metal disk 26 having a central bore 28 in which is slidably located a irlng pin 30 made of hardened steel and provided with a point at its lower end where It rests on top of the percussion cap 24 as indicated. The top of the iiring pin 30 projects above the top of the ash producer 8 as shown. A closingy plate or cover 32 is threaded to the reduced upper portion 34 of the housing I0. The cover 32 has a threaded recess 36 to engage the external threads 38 on the reduced portion 34 of the housing.

It is to be noted that the upper surface of the disk 26 projects slightly above the upper surface 40 of the housing I0, so that as the cover 32 is tightened downward, it serves to compress the gasket I8 tightly and also the rim' of the -primer opposite recesses 42 so that a wrench having two matching dowels or studs may be used to rotate the cover by inserting the dowels into the recesses and turning the wrench clockwise to tighten and f counterclockwise Vto loosen it. '.Ihey cover 32 may also be turned by applying a pipe wrench to its peripheral surface, in the usual manner for cylindrical surfaces. The cover 32 has a central aperture 44, through which the firing pin' 30 prei*4 trudes.

A horizontal radial bore 46 connects the chamber I4 to the outside of the housing III. The bore 3 48 has a reduced inner portion 48 and an enlarged outer portion 88, the portion 88 being threaded at itsouter end 82. An annular copper gasket 84.*having its insidediameter equal to that of bore 48 an'd its outside diameter equal to the diameter of bore 88, is locatedin the inner end of bore 88. A cylindrical member 88 having a central bore 88' with a reduced portion 88 and an enlarged portion 82 is located in bore portion 88 next to gasket 84 as indicated. The diameter of portion 82 of the bore 58 is equal to that of bore portion 48.

A hollow member 84 having external threads 88 is threaded into the threaded outer portion V82 of bore portion 58. The member 84 has a projecting portion 88 which is hexagonal in diametral cross section so it may be engaged with a hexagonal-Wrench for turning the member 84 into or out of engagement with the threaded portion 52. The member 84 has a frustro-conical shaped central opening 18, which expands outwardly as shown. Bytightening member 84, the gasket 54 is compressed and the chamber |4 communicates with the Loutside of casing |8 through a flash passageway 85 comprising the bore portions 48, 82. 88, and opening 18.

A base plate disk 12 serves as a base for the housing |8 and is fastened to the underside of housing I8 by means' of screws 14 passing through openings in the disk 12 and threaded into recesses 18 in the housing I8. Holes 18 in disk 12 enable the disk 'and housing to be removably secured to the top member of platform 2 by placing the disk so the holes 18 fit over matching projecting studs or dowels 88 projecting upwardly from surface 4 and secured to the platform. The housing |8 is reduced in diameter at its lower end 82, .the reduced end 82 iltting into a matching recess 84 formed in the upper surface of base plate 12.

The platform 2 has a central longitudinal elongated aperture or slot 88 formed through its top member 5. An L-shapedfmember or support 8 has a vertical leg 88 and a horizontal leg 98. In order to vary the distance of the support 8 from the flash producer 8, the. horizontal leg 88 is provided with a. lower horizontal elongated guide projection or tongue 82 which projects downwardly into the slot 88 and thus serves to constrain the support 8 to horizontal movement along the slot toward or away from the flash producer. To keep the tongue 82 from vertical motion, a member 84 is provided, a detail perspective view of it being shownvin Figure 9. The member 84 has an upward projection 98 fltting into the slot 88 to a distance sufilcient for its upper surface to vtouch the lower surface of tongue `82. The member 84 has a central vertical aperture 88 which is square in horizontal cross section. A bolt |88 having around head |82 projects upwardly through the aperture 88, the shank of the bolt being square in cross section for a distance equal to the thickness of member 84. and of the same cross section as the aperture 88. The rest of the shank of the bolt |88 is round in cross section as it passes through a hole ,I 84 in horizontal leg 88, and its upper end, protruding above hole |84 is threaded into a wing nut |88 by which the support 8 may be tightly secured in position at any desired point along slot 88;

The vertical leg 88 has an aperture |88 having its axis parallel to slot 88. A cylindrical member ||8 extends into aperture |88, and has a collar ||2 bearing against the surface of the leg 88 around the aperture. A soft lead equal in diameter to the outside diameter of member ||8 as shown and about n1 of an inch thick, is placedagainst the end ||4 of member H8, closing it. A hollow cylindrical non-inflammable member ||8, about one-sixteenth of an inch thick and having an inside diameter equal to the diameter of disk ||3 extends over the disk and the endl |4 of member ||8, thereby holding the disk I|8 against member ||8. ,Member ||8 has a reduced portion ||8 equal in inside diameter tothe outside diameterof the fuse |28 which is being tested and is inserted into the reduced portion ||8 as shown. Cellulose acetate has been found to be a suitable material for making member I I8.

As shown in the detail cross section of the fuse I 28 in Figure 4, the fuse |28 comprises a hollow cylindricalv casing |22 usually made of aluminum and has its open ends |23 and |25 reduced in the diameter of the openings by spinning or other suitable process. Inside one end |28 is located a very thin disk |24 made of aluminum foil about one thousandth of an inch in thickness, but the thickness may be greater or less depending on the specifications. The heat sensitive lead azide |28 is then placed inside the casing |22 and also, if desired. some tetryl |28. The thin disk |24 may be coated on its inside or outside surface with a seal coat and/or lacquer although the coating is omitted in some fuses. The fuse |28 is placed in the reduced end ||8 with its end |23, containing the disk |24, facing rthe two disks 28 and 28 lifted out.

toward the flash producer outlet 18. It is to be understood that this invention does not relate to the construction of the detonator |28 but rather to the means of testing of any detonators which it is desired to test for sensitivity to heat.

The operation of the device may now be described briefly. The cover 82 is removed from the flash producer 8 and the firing pin 38 and A small quantity |38 of a double base powder such as Ballistite, or a smokeless powder such as E. C. powder, is placed in the chamber i4 and a Western No. 3 percussion primer placed in the central opening 22 in disk 28 and then the cover, firing pin and disks are-replaced, the cover being screwed on tightly. It is better to use Ballistite powder or an equivalent double base powder because it produces less slag particles as a residue and in the flame than smokeless powder.` It was found undesirable to use more than 5 grains of Ballistite in the flash producer described above. A soft lead diskA ||3 is placed within the'end of plastic member ||8 having the larger diameter. The plastic member is then placed over the projecting end of member ||8. A detonator |28 is inserted into the reduced portion ||8 of the plastic member, the end |23 usually extending outward and facing the-source of the flame. A weight is then dropped onto the projecting rlng pin 38. setting off the primer 24 and exploding the charge |38. A flash of hot gases `and flame resulting frorn'the explosion of the charge shoots out through the flash passage 55 and the flash is projected against the detonator |28 being tested. If the heat reaching the contents of detonator |28 is sufficient and the detonator is otherwise sensitive, it will explode and cause a hole to be blown right through the soft lead disk I4. Thus the existence of such a hole in disk I4 indicates that the detonator |28 has exploded with a high order explosion, that is, a very rapid explosion amounting to detonation, while if no disk m specic terms, it is to be understood that numerous changes may be made in the size, shape, arrangement and materials without departing from the scope and spirit of the invention.

I claim:

1. A device for testing a detonator, comprising a housing having a chamber formed therein for the reception of an explosive charge, means for exploding said charge whereby burning gases are produced in said chamber, outlet means whereby said gases may escape from said housing, and means for supporting a detonator in the path of said escaping gases.

2. A device for testing a detonator, comprising a housing having a chamber formed therein for the reception'of an explosive charge, means arranged in said housing for exploding said charge whereby burning gases are produced, outlet means constructed and arranged for permitting' .said gases to escape from said housing. means for supporting a detonator in the path of said escaping gases, said means being constructed and arranged for varying the spacing between said detonator and said outlet means.

3. A device for testing a detonator, comprising a housing having a chamber formed therein for the reception of an explosive charge, Omeans arranged in said housing for exploding said charge -whereby burning gases comprising a flame are produced, outlet means constructed and arranged for permitting said ilame to escape from4 said housing, means constructed and arranged for supporting a detonator in the path of said escaping name, said means being constructed and arranged for varying the distance of said detonator from said outlet means.

c 4. A device for testing a detonator, comprising a support, a hollow housing having achamber therein andconstructed and arranged on said support for producing burning -gases within said chamber, means constructed and arranged for projecting said gases out of said last named means, support means constructed and arranged on said support for supporting a detonator in the path of said projected gases, and means constructed and arranged for varying the spacing between said detonator support means and said gas producing means. l

5. A detonator testing device comprising on a base, means constructed and arranged for producing and projecting a flame, and support means constructed for holding a detonator in the path of said flame, said support means being slidably arranged on said base and provided with locking means constructed and arranged for securing said support to said base at any desired point in said path, said support means having an upwardly projecting member having a horizontal aperture formed therein',` a lead disk arranged over said aperture, closing the same, and means constructed and arranged for holding a detonator against the outer face of said lead disk, said disk and detonator being located on the side of said aperture nearest to said llame.

6. A device for producing a iiash of iiame for testing detonators, comprising a housing having a chamber formed therein for the' reception of an explosive charge, means constructed and arranged in said housing for exploding said charge whereby burning gases-comprising a ame are produced, outlet orifice means constructed and arranged for permitting said flame to escape fromsaid housing, and nozzle means constructed and arranged for guiding said name along a path outside said housing into Contact with a detonator being tested.

7. In a device arranged on a base for testing detonators by applying a flash of ame from a flame producer to said detonators, a device for holding a detonator in the'path of said iiame, comprising an upwardly projecting member movably arranged on said base and provided with locking means constructed and arranged for securing said member to said base at any desired REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,554,993 Ettele Sept. 29, 1925 1,615,606 Wohler Jan. 25, 1927 2,323,301 Anderson July 6, 1943 2,377,425 Jackson June 5, 1945 

